The State Water Resources Control Board is recommending that California fund efforts to mitigate nitrate pollution through a statewide fee on fertilizer.

In a report to the Legislature, the board said that groundwater nitrate pollution in the Tulare Lake Basin and Salinas Valley is likely to get worse in the future, and a dedicated funding stream is needed to address the problem.

Agricultural fertilizer and confined animal facilities are considered some of the top sources of nitrate pollution.

More than half of California's population relies on a contaminated drinking water supply – though most communities blend or treat their water to make it safe. Ben Adler has more from Sacramento on that finding in a new state report out this week.

The report by the State Water Resources Control Board was ordered by the state Legislature. It says from 2002 to 2010, 680 out of 3,000 community water systems in the state relied on one or more contaminated groundwater wells. Those contaminated wells served 21 million people.

The San Joaquin Valley’s polluted air is a daily concern for Mario Talavera.

“When I go to the pharmacy, they ask why I need medicine," said Talavera, of Fresno. "For Mario, Angelica, Tomas, Jose. And for me too, Mario. I have asthma. The only person who doesn’t have asthma is my wife.”

It’s a constant stress for Fresno resident Teresa Vidales, too. Her husband, a construction worker and the family breadwinner, has asthma. One of her four kids does, too.

Two hazardous waste facilities in the San Joaquin Valley led the state in toxic chemical releases in 2011, according to a report released today by the Environmental Protection Agency.

The Clean Harbors landfill in Buttonwillow in western Kern County ranked number one in the state in toxic releases, with nearly 10 million pounds in 2011. In Kings County, Chemical Waste Management’s Kettleman City disposal facility released nearly four million pounds in 2011, which ranked third in the state.

A new UC Berkeley study adds to research that suggests flame retardants common in California homes are linked to neurodevelopmental delays in kids.

The study followed nearly 300 women from pregnancy to when their children were 7 years old. Researchers tested mother's levels and then the children's levels for the flame retardant compound polybrominated diphenyl ethers, known as PBDE. They wanted to assess in utero effect as well as childhood exposure, says lead researcher and UC Berkeley epidemiologist Brenda Eskenazi.

The small Kern County community of Arvin has some of the worst air in the nation. Surrounded on two sides by mountains at the southern end of the San Joaquin Valley, the city's 16,000 residents breathe air polluted by cars, trucks and industrial operations from nearby, and from across the valley. But now some members of the community are taking matters into their own hands, with a "bucket brigade" that aims to clean up the air. But their efforts are not without controversy.

Two major environmental groups have filed suit against the California State Department of Public Health for what they call a failure by the state to set rules for the safe amount of a toxic chemical in drinking water. Hexavalent chromium, also known as chromium-6, gained widespread attention as the chemical that sickened residents in the film Erin Brockovich.

Residents in the Fresno County town of Easton get their water from backyard wells. But many of those wells recently tested above the official limit for certain toxins. It's just the latest case of rural San Joaquin Valley residents struggling to find safe water to drink. Dan Morain of the Sacramento Bee reports.

The California Air Resources Board has created a map that shows the state’s biggest emitters of greenhouse gases. It is a significant step in the development of California’s Cap and Trade program.

On the new Google Earth map are 625 facilities that each produce more than 25,000 metric tons of greenhouse gases annually. The map breaks down facilities by industry, zip code and emissions. But, Stanley Young with the Air Resources Board says state-to-state comparisons aren’t yet available.

This week on Valley Edition we talk about this winter's especially poor air quality and learn what residents can do to stay healthy. We'll also talk about the once again stalled Fresno Veterans Home, and a program to help Valley residents make their homes more energy efficient.

On this week's Valley Edition we talk about efforts to end homelessness in the Valley. We also hear about the big water pollution problems facing the communities of rural Tulare County, and get a preview of the Big Fresno Fair.